Trailers with refrigeration units are typically used to ship and deliver frozen and/or perishable cargos. The refrigeration unit is generally mounted on the front outer wall of the trailer to maximize cargo space and includes a diesel engine for powering the refrigeration unit. In the loading and unloading of the cargo, a lift gate or platform is typically used to raise and lower the load. The lift gate or platform is operated through a hydraulic system. As disclosed in commonly assigned U.S. Pat. No. 4,688,391, the hydraulic system can be driven by the same power source as the refrigeration unit by unloading the refrigeration compressor responsive to the actuation of the hydraulic system. Both the pump and compressor are thus always driven but at least one is always in an unloaded or idled state. In the case of the hydraulic system, the hydraulic fluid is warmed by its continuing circulation through the pump. So, in addition to the energy loss due to driving the pump, even though it is unloaded, there is a requirement for a larger hydraulic fluid supply and reservoir in order to offset the heating effects of constant circulation through the pump. Also, this embodiment unloads the compressor whether required or not. The prime mover may be able to drive both the refrigeration unit and hydraulic system under some or all conditions. Where the cargo is made up of frozen, perishable and non-refrigerated items, each compartment may have its own lift gate or platform.